This invention relates to the treatment of underground formations to provide stoppages or plugs within the formation. In one of its aspects this invention relates to the creation of plugs in an underground formation under controlled conditions of pH. In another of its aspects this invention relates to the temporary plugging of an underground formation and the removal of gelled stoppages by controlling the pH of liquid in contact with the stoppages.
The advantages of using gel forming compositions for controlling the permeability of underground formations during waterflooding and chemical flooding operations is well known in the art. These plugging techniques are also used during well workovers, in fracture treatments, and to correct the injection profile of a well by sealing high permeability streaks so that flooding fluids will enter the formation in a more desirable front. In some of these operations it is desirable to temporarily plug a portion of an underground formation to direct treating fluids into certain zones of the formation and then remove the stoppages from the formation after the particular treatment is completed.
It is an object of this invention to provide a method which can be used either for permanent or temporary plugging of underground formations. It is also an object of this invention to provide a method for treating an underground formation in which the plugging can be controlled by control of the pH of fluids in contact with the plugging agent.
Other aspects, objects and the various advantages of this invention will become apparent upon reading this specification and the appended claims.